Pillar and stall mining roof support



E.- HOLLAND May 19, 1970 PILLAR AND STALL MINING ROOF SUPPORT Filed June1-8, 1 968 3 Sheets-Sheet 1 -ET Q:

INVENTORZ ELLIS HOLLAND ATTORNEY.

E. HOLLAND PILLAR AND STALL MINING ROOF SUPPORT May 19, 1910 3Sheets-Sheet 2 Filed June 18, 1968 United States Patent 3,512,364 PILLARAND STALL MINING ROOF SUPPORT Ellis Holland, Sheffield, England,assignor to A. G. Wild & Co. Limited, Sheflield, England, a Britishcompany Filed June 18, 1968, Ser. No. 737,884 Claims priority,application Great Britain, June 19, 1967, 28,189/ 67 Int. Cl. E21d 23/00US. Cl. 61-45 9 Claims ABSTRACT OF THE DISCLOSURE A self-advancingsupport having an elongated roof engaging member with a cantileverextension, said member being attached solely by a pivot means to a rearchock and slidably supported by a forward chock during all modes ofoperation. Hydraulic ram means is provided to effect raising andlowering of the chocks and at the sides of the corresponding bases toadvance the support. The member includes spaced beams and a cross plateand levers operate said beams from the forward chock. Arms on saidforward chock provide auxiliary support for said member.

This invention relates to a hydraulically operated self advancing mineroof support and is particularly suited for use in seams mined on thepillar and stall system and to a pillar and stall method of mining usingsuch a suport. p For the purpose of explanation of the background of thepresent invention, reference will now be made to FIG. 1 illustrating inplan a pillar and stall system.

The seams in the pillar and stall mining system are divided into areasknown as panels, these panels being say 300 yards square. Main headings110 or entries are then driven into these panels, the headings being atright angles to the main joint in the coal seams and for example about18 ft. wide. Cross headings 112 or entries are then driven at rightangles to the main headings or entries, these cross headings being about12 ft. wide. The main headings and cross headings are spaced at about120 ft. intervals, at centres commensurate with the depth of theWorkings and geological conditions thus leaving untouched pillars 114 ofmineral for example 100 ft. square, which serve to temporarily supportthe roofs of the headings.

When all the pillars in the panel have been formed the pillars areextracted by commencing with the pillar furthest from the main mine exitand then extracting subsequent pillars in such a pattern so that thebreakdown or caving of the roof advances in a diagonal manner, theadvancing front 116 of the caving being knownas the Fracture Line.

Generally the pillars are extracted in slices 118, each slice being forexample about 9 ft. wide, starting from the goaf side and workingtowards new pillars. As extraction proceeds the roof has to be supportedand when the slice has been finished the supports have to be advanced.

Modern practice is for the extraction to be carried out by machinery,for example a cutting machine having rotary cutting heads at its forwardend and a self-loading conveyor at its rear end. In operation theconveyor feeds the cut mineral into a self-propelled mine car or shuttlecar.

The normal practice of supporting the roof is to have wooden chocksnearest the goaf and then between these wooden supports and the pillarare placed simple props and roof bars to provide support over theworking road- Patented May 19, 1970 ice way. This system of supportingis neither self-advancing nor normally sufficiently wide to allow thepassage of shuttle cars.

To briefly summarize the present invention, We provide a fluid-operableself-advancing mine roof support particularly for use in pillar andstall mining comprising a rear fluid-operable chock and at least oneother fluidoperable chock, in which a roof-engaging member ofsubstantial length is pivotally attached only to the rear chock at ortowards the top thereof and extends forwardly adjacent and in slidablerelationship during all modes of operation with a canopy unit providedat the top of the chock or each other chock, the bases of the rear chockand one of the other chocks being connected by a double-actingfluid-operable ram for use in advancing the support.

In such a mine roof support comprising a forward and a rear chock, theforward chock can be advanced independently of the rear chock. Theadvancing means of the support is formed by double acting hydraulic ramsconnected between said legs. The rear ends of the cylinders of said ramsmay be pivotally connected to the sides of the base of the front leg andthe outer ends of the piston rods of said rams may be pivotallyconnected to the sides of the base of the rear leg. The roof member maybe for example two parallel beams, one on each side, which extendforwardly and slidably pass over supporting wings within the canopy uniton the top of the front chock. The two said beams extend a considerabledistance, for example 9 feet in front of the forward leg and are joinedtogether at the forward end of the beams by a large cover plate.

In one embodiment of the invention, two L-shaped levers are pivotallyconnected to the top of the front leg, the long arms of the leversextending forward. These arms are joined together at their ends by asupporting bar, which passes underneath the aforesaid beams.

Pressure capsules may be provided to act on the short arms of theL-shaped levers which in turn forces the supporting bar onto theunderside of roof beams and thus forces connecting cover plate intocontact with mine roof.

The invention will be better understood from the following particulardescription given by way of example with reference to the accompanyingdrawings in which:

FIG. 1 is as stated, a plan view of a panel of a seam mined by theroom-and-pillar system of mining.

FIG. 2 is an elevation of one form of roof support according to theinvention.

FIG. 3 is a diagram showing the sequence of operations used to advancethe supports in accordance with the method of the invention.

FIG. 4 is a cross-sectional view taken along line IV-- IV of FIG. 2.

FIG. 1 shows one panel of a seam which has been divided by lateralroadways or main entries and longitudinal roadways or cross entries. Themain entries may be 18 feet wide whilst the cross entries may be 12 feetside. Pillars of coal are formed by the said system of tunneling whichmay be feet square.

The pillars, shown in dotted lines and hatched over as at 122 are onesthat have been extracted and the roof allowed to cave-in to form goaf.Pillars are extracted in turn in such a manner as to form of diagonalfracture line.

The chain dotted lines and serial Nos. 1-10 shown on one of the pillars(114a) indicate how the mineral, e.g. coal will be extracted in stripsof about 10 feet width, the numbers being the order in which the stripsare worked.

Now, referring to FIG. 2, this shows one form of roof support accordingto the invention comprising a rear hydraulically extensible rear chock 1sitting on a base unit 2 and carrying a canopy unit 3 at its upper end.A front hydraulically extensible chock 4 sits on a base unit 5 which issimilar to base unit 2 but of opposite hand, and also carries a canopyunit 6. Two double acting advancing rams 7 are situated one on each sideof the legs 1 and 4. The cylinders of these rams are pivotally connectedat 8 to a clevis 9, the opposite end of which is pivotally connected at10 by means of a pin in a vertically slotted hole to a bracket 11. Thebracket 11 is rigidly attached to base 5. The piston rods of the rams 7are similarly connected to rear base unit 2.

Two roof bars members 12 situated one on each side of legs 1 and 4 arepivotally connected at 13 to rear canopy unit 3. These bars 12 extend aconsiderable distance, for example 9 feet in front of leg 4 and arejoined together by roof bar cover plate 14 to form a cantileverextension. This is in contrast to conventional constructions of roofsupport for longwall mining in which the roof bars normally extend onlyabout 3 ft. in front of the forward leg. The members 12 extend forwardlythrough and in slidable relationship with the canopy unit 6.

The two L-shaped levers 15 are pivotally connected at 16 to brackets 17.The longer arms 15a of said levers extend forwardly and are joinedtogether by a support bar 18. Pressure capsules 19, i.e. small singleacting rams, are situated one on each side of leg 4. The cylinders ofsaid capsules are pivotally connected at 20 to a bracket 21 Whilst thepistons of said capsules are pivotally connected at 22 to the shorterarm 15b of L-shaped levers 15.

When pressure capsules 19 are pressurised they exert a force on theshorter arms of levers 15 and thus cause support bar 18 to be forcedonto the undersides of roof bars 12 thus causing said bars to pivotabout pivot 13 until the roof bar cover plate 14 contacts the roof ofthe mine. Removing pressure from capsule 19 causes the weight of members12, 14 and 15 to compress the capsule 19, thus lowering the bars 12until they come to rest on supporting arms 23, which protrude fromundersides of canopy unit 6 as shown in FIG. 4.

With capsules in compressed (i.e. retracted) condition, the front leg 4can be lowered from the roof, leaving rear leg 1 still set to the roof,and then rams 7 are operated to extend and push leg 4 towards the coalface a distance equal to half the cantilever length. The cantileverlength will be of the order of 9 ft. and therefore the stroke of therams 7 will be about 4'6". When leg 4 has been fully pushed over it isreset to the roof and then rear leg 1 lowered from the room. Rams 7 arethen operated to compress and pull leg 1, plus attached roof bars 12, adistance of 4'6" towards leg 4. Leg 1 is then reset to the roof. To movesupport over the full 9 ft. width of roadway the above operation must becarried out twice. After support has been fully moved over capsule 19 isre-pressurised and cover plate 14 reset to the roof. To assist loweringof legs 1 and 4 from the roof, retraction rams 24 are positioned on eachleg.

To offer the greatest support to the roof the supports are positioned atabout 4 ft. centres and when the cut has been taken the supports areadvanced in pairs using a sequence according to the invention thatensures maximum roof support throughout the advancement. FIG. 3 showsthe sequence of operations involved in the method according to theinvention in which the full lines indicate the position of the firstsupport of the pair and the dotted lines indicate the position of thesecond or adjacent support in relation to the first support. The numbersshown in FIG. 3 correspond to the sequence numbers specified in thefollowing paragraphs.

The sequence of operations in accordance with the method of miningaccording to the invention, to advance a pair of supports is as follows:

(1) Cantilever extension and front leg of first support are loweredwhilst second support remains fully raised.

(2) Advancing rams of first support are operated to push front legforward and then front leg reset to the roof.

(3) Cantilever extension and front leg of second support are loweredthen advancing rams of second support are operated to push front legforward and then front leg reset to the roof.

(4) Rear leg of first support is lowered and advancing rams operated topull rear leg and cantilever extension forwards. Rear leg then reset tothe roof.

(5) Rear leg of second support is lowered and advancing rams operated topull rear leg and cantilever extension forward. Rear leg then reset tothe roof.

(6) Front leg of first support is lowered and advancing rams operated topush front leg forwards and then front leg reset to the roof.

(7) Front leg of second support lowered and advancing rams operated topush front leg forwards and then front leg reset to the roof.

(8) Rear leg of first support is lowered and advancing rams operated topull rear leg and cantilever extensions forwards. Rear leg andcantilever extension are both reset to the roof. The first support hasnow been fully advanced.

(9) Rear leg of second support is lowered and advancing rams operated topull rear leg and cantilever extension forwards. Rear leg and cantileverextension are both reset to the roof. The second support has now beenfully advanced.

The above sequence of operations are repeated on the next pair ofsupports and so on down the face until all sulpports have been fullyadvanced. The supports can be advanced as the cut proceeds or When thecut has been finished.

Each support will be controlled independently, the control panel beingpositioned on the front leg so as to always be furthest away from thegoaf.

The support system could be automatically advanced by a remotelyoperated control system.

The support disclosed herein, while particularly suitable forroom-and-pillar work, could be used in any type of mining where a deepcut is required to be taken. such as would arise if using a wide webbuttock mining machine.

I claim:

1. A fluid-operable self-advancing mine roof support particularly foruse in removing wide webs of mineral comprising a rear base, a rearchock mounted on said rear base, a base located forwardly of said rearbase, a forward chock mounted on said forwardly located base, fluidmeans for operating said chocks, an integral roof engaging member ofsubstantial length solely attached to said roof support by pivot meansadjacent the top of said rear chock, said member extending adjacent theforward chock, means for slidably supporting said member by said forwardchock during all modes of operation, the roof engaging member havingsufiicient length to extend beyond said forward chock to form acantilever extension, and the bases of the rear chock and the forwardchock being connected by at least one double-acting fluid-operable ramfor use in moving said support.

2. A support according to claim 1 in which said fluid means includeshydraulic ram means connected between the topof at least one of saidchocks and the corresponding one of said bases to effect raising andlowering of the chock.

3. A support according to claim 1 in which said supporting meansincludes adjustable means on said forward chock for raising and loweringsaid extension.

4. A support according to claim 3 in which said adjustable meanscomprises an L-shaped lever pivotally carried by the forward chock toengage the cantilever extension of the roof engaging member, and afluid-operable ram is provided for pivoting the lever to urge saidextension against the roof.

5. A support according to claim 3 wherein said supporting means furtherincludes an arm carried by said forward chock adjacent the top thereoffor slidably engaging said cantilever extension from below whereby saidextension is additionally supported by said forward chock when saidadjustable means is in the lowered position.

6. A support according to claim 1 wherein said doubleactingfluid-operable ram is connected between the forward and rear chock basesat one side thereof, and an additional double-acting fluid-operable armis provided at the opposite side of said base to aid in moving saidsupport, said rams being pivotally connected to said bases at both ends.

7. A support according to claim 1 wherein said roof engaging membercomprises two parallel beams connected to the free ends by a crossplate.

8. A support according to claim 7 wherein said sup- 20 porting meansincludes adjustable means on said forward chock for raising and loweringsaid extension, said adjustable means comprises L-shaped leverspivotally carried by the forward chock to engage said beams, a cross barto connect said levers and fluid-operable ram means is provided forpivoting the levers tourge said extension against the roof.

9. A support according toclaim 8 wherein said supporting means furthercomprises protruding arms extending from the sides of said front chockfor auxiliary sliding support of said beams when said levers arelowered.

References Cited UNITED STATES PATENTS 3,372,551 3/1968 Von Hippel 6145FOREIGN PATENTS 202,954 4/ 1959 Austria. 719,170 11/1954 Great Britain.882,933 11/1961 Great Britain. 1,427,549 12/ 1965 France.

942,384 5/ 1956 Germany. 140,778 1/1961 U.S.S.R.

DENNIS L. TAYLOR, Primary Examiner US. Cl. X.R. 248357

